WO2010087429A1

WO2010087429A1 - Antenna and wireless ic device

Info

Publication number: WO2010087429A1
Application number: PCT/JP2010/051205
Authority: WO
Inventors: 加藤　登; 佐々木　純; 哲平三浦; 直樹郷地
Original assignee: 株式会社村田製作所
Priority date: 2009-01-30
Filing date: 2010-01-29
Publication date: 2010-08-05
Also published as: JP5267578B2; CN102301528B; CN102301528A; EP2385580A1; JPWO2010087429A1; EP2385580B1; EP2385580A4; US9104950B2; US20110279340A1

Abstract

Disclosed are an antenna for wireless IC devices that has good energy transmission efficiency with wireless ICs, and a wireless IC device that is equipped with said antenna. An antenna (30) comprises a coil pattern (31) and spiral coupling patterns (32a, 32b), which are formed at both ends of said coil pattern (31) and are disposed facing one another. A wireless IC device (1A) is configured by installing a coupling module (20), comprising a wireless IC chip (21) and a power supply circuit substrate (25) which has a power supply circuit that couples with said wireless IC chip (21), on the coupling pattern (32a). The coil pattern (31) is an open type that, with the adjacent coupling patterns (32a, 32b), overall forms a single LC resonator, which improves the energy transmission efficiency between the antenna (30) and wireless IC chip (21) by focusing energy to the coupling patterns (32a, 32b).

Description

Antenna and wireless IC device

The present invention relates to an antenna and a wireless IC device, and more particularly to an antenna for a wireless IC device used in an RFID (Radio Frequency Identification) system and a wireless IC device including the antenna.

2. Description of the Related Art Conventionally, as an article management system, a reader / writer that generates electromagnetic waves communicates with a wireless IC (referred to as an IC tag or wireless IC device) that stores predetermined information attached to an article or a container in a non-contact manner. RFID systems that transmit information have been developed. The wireless IC can communicate with a reader / writer by being coupled with an antenna (radiation plate).

As this type of wireless IC, in Patent Document 1, as shown in FIG. 14, the coil L11 of the ID module 100 and the coil L12 of the coil module 110 are coupled and resonated at a predetermined frequency. Are listed. The ID module 100 causes the primary coil L11 and the capacitor C11 to resonate in parallel. The coil module 110 is configured in a closed loop by electrically connecting both ends of the two coils L12 and L13, and energy is transmitted between the two coils L12 and L13 by current. That is, the magnetic field is radiated by the current generated by the coil L12 coupled to the primary coil L11 passing through the coil L13.

However, if the inductance value of the radiation coil L13 is increased and the inductance value of the coupling coil L12 is decreased in order to increase the received magnetic field energy from the reader / writer, the voltage across the coil L12 decreases. Therefore, the amount of current flowing between the two coils L12 and L13 is reduced, and sufficient energy is not transmitted from the IC to the radiating coil L13, resulting in a problem that the communication distance is reduced. Further, when the radiating coil L13 is close to the reader / writer antenna or close to another wireless IC, its value changes due to mutual inductance, and the resonance frequency of the primary coil L11 also changes. As a result, there is a possibility that reading with a reader / writer becomes impossible.

Japanese Patent Laid-Open No. 10-293828

Therefore, an object of the present invention is to provide an antenna for a wireless IC device having high energy transmission efficiency with the wireless IC, and a wireless IC device including the antenna.

In order to achieve the above object, the antenna according to the first aspect of the present invention is:
With antenna pattern,
A spiral coupling pattern coupled to the antenna pattern and disposed opposite to each other;
It is provided with.

The wireless IC device according to the second aspect of the present invention is
With antenna pattern,
A spiral coupling pattern coupled to the antenna pattern and disposed opposite to each other;
A coupling module comprising a wireless IC and a power feeding circuit board having a power feeding circuit coupled to the wireless IC;
With
The power supply circuit includes an inductor;
The coupling module is mounted on the coupling pattern;
It is characterized by.

In the antenna and the wireless IC device, the spiral coupling patterns coupled to the antenna pattern are arranged to face each other to form one LC resonator. That is, a capacitance is formed between the spiral coupling patterns arranged opposite to each other, and LC resonance is caused by the inductance formed by the capacitance and the spiral coupling pattern. Due to this LC resonance, the impedance becomes infinite, and energy concentrates on the coupling pattern. As a result, energy transmission efficiency between the antenna and the wireless IC mounted thereon is improved.

In the antenna and the wireless IC device, the antenna pattern may be a single coiled pattern, two coiled patterns arranged opposite to each other, or at least a pair of end portions. And two dipole patterns disposed opposite to each other and having a dipole-type radiator coupled to the ring pattern. In particular, if the antenna pattern is disposed so as to face two layers, more magnetic fields can be generated. Furthermore, if two antenna patterns and two coupling patterns are connected to each other, even if a plurality of wireless IC devices are close to each other or a dielectric such as a human hand is close to the pattern, The occurrence of stray capacitance is suppressed, and fluctuations in the resonance frequency are prevented.

According to the present invention, the transmission efficiency between the antenna and the wireless IC is improved, and energy is transmitted efficiently.

It is sectional drawing which shows the radio | wireless IC device which is 1st Example. It is a perspective view which shows the principal part of the radio | wireless IC device which is 1st Example. It is a perspective view which expands and shows the pattern for a coupling | bonding of the radio | wireless IC device which is 1st Example. It is a top view which decomposes | disassembles and shows the laminated structure of the electric power feeding circuit board mounted in the radio | wireless IC device which is 1st Example. It is a perspective view which shows the principal part of the radio | wireless IC device which is 2nd Example. It is a top view which expands and shows the pattern for a coupling | bonding of the radio | wireless IC device which is 2nd Example. It is the equivalent circuit schematic of the antenna which comprises 1st Example. It is the equivalent circuit schematic of the antenna which comprises 2nd Example. It is a top view which shows the radio | wireless IC device which is 3rd Example. It is a top view which shows the antenna pattern provided in the surface side of the radio | wireless IC device which is 3rd Example. It is a top view which shows the antenna pattern provided in the back surface side of the radio | wireless IC device which is 3rd Example. It is a top view which decomposes | disassembles and shows the laminated structure of the electric power feeding circuit board mounted in the radio | wireless IC device which is 3rd Example. It is a graph which shows the gain of the radio | wireless IC device which is 3rd Example. It is an equivalent circuit diagram showing an example of a conventional wireless IC device.

Embodiments of an antenna and a wireless IC device according to the present invention will be described below with reference to the accompanying drawings. In addition, in each drawing, the same code | symbol is attached | subjected to the same member and part, and the overlapping description is abbreviate | omitted.

(Refer to the first embodiment, FIGS. 1 to 4 and 7)
As shown in FIGS. 1 and 2, the wireless IC device 1 </ b> A according to the first embodiment includes a substrate 10, a coupling module 20, and an antenna 30. The coupling module 20 includes a wireless IC chip 21 and a power feeding circuit board 25 having a power feeding circuit coupled to the wireless IC chip 21. The antenna 30 includes a coiled pattern 31 and

spiral coupling patterns

32a and 32b that are formed at both ends of the coiled pattern 31 and are arranged to face each other.

The substrate 10 is made of a dielectric material such as a PET film. The coil pattern 31 is formed in a coil shape on the surface of the substrate 10 as shown in FIG. 2, and a spiral coupling pattern 32a is formed at one end. A spiral coupling pattern 32 b is disposed on the back surface of the substrate 10 so as to face the coupling pattern 32 a, and an end 32 c of the coupling pattern 32 b is connected to the other side of the coiled pattern 31 via the via-hole conductor 33. Is electrically connected to the end portion 31c.

As is conventionally known, the wireless IC chip 21 includes a clock circuit, a logic circuit, a memory circuit, and the like, and stores necessary information. An input terminal electrode, an output terminal electrode, and a mounting terminal (not shown) An electrode is provided. As will be described below with reference to FIG. 4, the power supply circuit board 25 is a laminated board including a power supply circuit including an inductor, and is mounted (adhered) on the coupling pattern 32 a. The coupling module 20 may be one in which the wireless IC chip 21 and the power feeding circuit board 25 are separately formed, or the wireless IC and the power feeding circuit may be integrally formed on one board. Good.

Here, an example of a power feeding circuit built in the power feeding circuit board 25 will be described with reference to FIG. The feeder circuit board 25 is a laminate of a plurality of sheets 41a to 41g each having an electrode, and each of the sheets 41a to 41g is made of ceramic or resin.

In the sheet 41a, electrodes 42a to 42d and via-hole conductors 43a and 43b are formed. On the sheets 41b to 41f, electrodes 44 and via-hole conductors 43c and 43d are formed. An electrode 44 is formed on the sheet 41g.

By laminating the sheets 41a to 41g, the respective electrodes 44 are electrically connected via the via-hole conductors 43d to form inductors. One end of the inductor (one end 44a of the electrode 44 on the sheet 41b) is connected to the electrode 42b on the sheet 41a via the via-hole conductor 43b. The other end of the inductor (one end 44b of the electrode 44 on the sheet 41g) is connected to the electrode 42a on the sheet 41a via the via-hole conductors 43c and 43a. The inductor resonates at a predetermined resonance frequency with its own inductance and the capacitance between the electrodes 44.

The electrodes 42a and 42b on the sheet 41a are connected to the input terminal electrode and the output terminal electrode of the wireless IC chip 21, respectively. The electrodes 42c and 42d on the sheet 41a are connected to the mounting terminal electrodes of the wireless IC chip 21. The inductor is magnetically coupled to the

coupling patterns

32a and 32b.

In the wireless IC device 1A having the above configuration, a high frequency signal (for example, UHF frequency band or HF frequency band) radiated from the reader / writer is received by the coiled pattern 31 and magnetically coupled to the

coupling patterns

32a and 32b. The power feeding circuit is resonated, and only the reception signal having a predetermined frequency is supplied to the wireless IC chip 21. The wireless IC chip 21 takes out predetermined energy from the received signal, reads out information stored in memory using this energy as a drive source, matches it with a predetermined frequency by a power feeding circuit, and then passes through the

coupling patterns

32a and 32b. The signal is radiated from the coiled pattern 31 as a transmission signal and transmitted to the reader / writer.

The coiled pattern 31 is an open type, and the

coupling patterns

32a and 32b located at both ends of the coiled pattern 31 are close to each other, and the

coupling patterns

32a and 32b form an LC resonator (see FIG. 7). That is, a capacitor C is formed between the

spiral coupling patterns

32a and 32b arranged opposite to each other, and LC resonance is caused by the capacitors C and the inductances L1 and L2 formed by the

spiral coupling patterns

32a and 32b. . Due to this LC resonance, the impedance becomes infinite, and energy concentrates on the

coupling patterns

32a and 32b. As a result, the energy transfer efficiency between the antenna 30 and the wireless IC chip 21 mounted thereon is improved. In addition, the two

coupling patterns

32a and 32b that face each other are wound in opposite directions from each other in the plan view, so that the directions of current flow are the same and the directions of the magnetic fields coincide with each other. The degree is improved.

The resonance frequency of the power feeding circuit substantially corresponds to the resonance frequency of the transmission / reception signal. That is, the resonance frequency of the wireless IC device 1A is determined by the resonance frequency of the resonance circuit. Therefore, communication at the resonance frequency of the resonance circuit is possible regardless of the resonance frequency of the coiled pattern 31, and the power supply circuit board 25 having various resonance frequencies can be combined with one type of antenna 30. In addition, since the resonance frequency of the resonance circuit does not change due to the influence from others, the communication with the reader / writer is stable.

The resonance frequency of the coiled pattern 31 is preferably set higher than the resonance frequency of the resonance circuit included in the power supply circuit board 25. For example, when the resonance frequency of the power feeding circuit is 13.56 MHz, the resonance frequency of the coiled pattern 31 is set to 14 MHz. As a result, the power feeding circuit and the coiled pattern 31 are always magnetically coupled. If the antenna 30 is viewed alone, the communication distance becomes longer when the resonance frequency is close to the resonance frequency of the resonance circuit. However, in consideration of communication failure in the case of proximity to other wireless IC devices or proximity of a dielectric such as a human hand, the resonance frequency of the coiled pattern 31 is preferably set on the high frequency side.

The

coupling patterns

32a and 32b are arranged immediately below the magnetic field radiated from the power supply circuit board 25, and the inductor in the power supply circuit board 25 spirals so that current flows in the same direction as the

coupling patterns

32a and 32b. Since it is formed (FIG. 4 shows the direction A of the current flowing through the inductor and FIG. 3 shows the direction B of the current flowing through the

coupling patterns

32a and 32b), energy can be transmitted more efficiently.

The wireless IC chip 21 and the power supply circuit board 25 are electrically connected, but the power supply circuit board 25 and the antenna 30 need only be joined with an insulating adhesive. The direction of bonding is also arbitrary, and the area of the

coupling patterns

32a and 32b is larger than the area of the feeder circuit board 25. Therefore, alignment when the coupling module 20 is mounted on the coupling pattern 32a is extremely easy.

The power supply circuit board 25 is preferably made of a material containing a magnetic material. Even if the built-in inductor is small, the Q value becomes high, so that the feeder circuit board 25 can be made small. When the feeder circuit board 25 is formed of a plurality of layers, it is preferable that the permeability of the layer on the mounting surface side to the coupling pattern 32a is low (for example, a nonmagnetic layer). When the magnetic permeability is low, a magnetic field is likely to be generated in the vicinity of the outside, and the coupling is strong only with the

coupling patterns

32a and 32b, and also strong against interference from others.

(Refer to the second embodiment, FIG. 5, FIG. 6 and FIG. 8)
The wireless IC device 1B according to the second embodiment includes a substrate (not shown) (same as the substrate 10 in the first embodiment), the coupling module 20, and the antenna 50 shown in FIG. The antenna 50 is formed at two end portions of the

coiled patterns

51a and 51b disposed opposite to each other on the front and back surfaces of the substrate, and at one end of the

coiled patterns

51a and 51b, and disposed opposite to each other. It consists of

spiral coupling patterns

52a and 52b. The coupling module 20 is as described in the first embodiment, and is mounted (adhered) on the coupling pattern 52a. The communication mode between the wireless IC device 1B and the reader / writer is the same as that in the first embodiment.

Also in the wireless IC device 1B according to the second embodiment, the

coiled patterns

51a and 51b are of an open type, and are arranged between the

coiled patterns

51a and 51b arranged in opposition and between the

spiral coupling patterns

52a and 52b. A capacitor C is formed, and LC resonance is caused by inductances L1 and L2 formed entirely by the capacitor C, the two

coiled patterns

51a and 51b, and the

coupling patterns

52a and 52b (see FIG. 8). This LC resonance makes the impedance infinite, and energy concentrates on the

coiled patterns

51a and 51b and the

coupling patterns

52a and 52b. As a result, energy transmission efficiency between the antenna 50 and the wireless IC chip 21 mounted thereon is improved. Further, since two layers of the

coiled patterns

51a and 51b are arranged, more magnetic fields can be generated. Furthermore, since the two coil-

like patterns

51a and 51b and the

coupling patterns

52a and 52b are coupled to each other, a plurality of wireless IC devices are close to each other or a dielectric such as a human hand is present. Even if they are close to each other, stray capacitance is suppressed from occurring between patterns, and fluctuations in resonance frequency are prevented. Other functions and effects are the same as those of the first embodiment.

Incidentally, in the second embodiment, the entire antenna 50 resonates at a predetermined frequency. Therefore, when the coupling module 20 is mounted on the

coupling patterns

52a and 52b that are part of the antenna 50, the antenna 50 and the coupling module 20 are coupled only by a magnetic field at a predetermined frequency. The antenna 50 and the reader / writer are electromagnetic couplings.

(Refer to the third embodiment, FIGS. 9 to 13)
As shown in FIG. 9, the wireless IC device 1 </ b> C according to the third embodiment includes a substrate 110, a coupling module 120, and an antenna 130. The coupling module 120 includes a wireless IC chip 21 and a power feeding circuit board 125 having a power feeding circuit coupled to the wireless IC chip 21.

The antenna 130 (the front side is shown in FIG. 10 and the back side is shown in FIG. 11) has two

annular patterns

131a and 131b that have a pair of ends and are opposed to each other on the front and back surfaces of the substrate 110. The spiral coupling patterns 132a and 132b, which are formed at one end portions of the

annular patterns

131a and 131b and are arranged to face each other, are extended laterally from a part of the annular pattern 131a. And two radiators 133. Each of the radiators 133 is coupled to the annular pattern 131a and functions as a meandering dipole antenna.

An example of the power supply circuit board built in the power supply circuit board 125 will be described with reference to FIG. The power supply circuit board 125 is a laminate of a plurality of sheets 141a to 141d each having an electrode, and each of the sheets 141a to 141d is made of ceramic or resin.

In the sheet 141a, electrodes 142a to 142d and via-hole conductors 143a and 143b are formed. Sheets 141b and 141c are formed with electrodes 144 and via-hole conductors 143c and 143d. An electrode 144 is formed on the sheet 141d.

By laminating the sheets 141a to 141d, the respective electrodes 144 are electrically connected via the via-hole conductor 143c to form an inductor. One end of the inductor (one end 144a of the electrode 144 on the sheet 141b) is connected to the electrode 142b on the sheet 141a via the via-hole conductor 143b. The other end of the inductor (one end 144b of the electrode 144 on the sheet 141d) is connected to the electrode 142a on the sheet 141a via the via-hole conductors 143d and 143a. The inductor resonates at a predetermined resonance frequency with its own inductance and the capacitance between the electrodes 144.

The electrodes 142a and 142b on the sheet 141a are connected to the input terminal electrode and the output terminal electrode of the wireless IC chip 21, respectively. The electrodes 142c and 142d on the sheet 141a are connected to the mounting terminal electrodes of the wireless IC chip 21. The inductor is magnetically coupled to the coupling patterns 132a and 132b.

Also in the wireless IC device 1C according to the third embodiment, the

annular patterns

131a and 131b are open-type, and a capacitance is provided between the

annular patterns

131a and 131b arranged opposite to each other and between the spiral coupling patterns 132a and 132b. C is formed, and LC resonance is caused by inductances L1 and L2 formed entirely by the capacitor C, the two

annular patterns

131a and 131b, and the coupling patterns 132a and 132b. That is, the same equivalent circuit as in FIG. 8 is configured. Due to this LC resonance, the impedance becomes infinite, and energy concentrates on the

annular patterns

131a and 131b and the coupling patterns 132a and 132b. As a result, the energy transmission efficiency between the antenna 130 and the wireless IC chip 21 mounted thereon is improved. Therefore, the high-frequency signal is efficiently radiated from the radiator 133, and the high-frequency signal received by the radiator 133 is efficiently transmitted to the power feeding circuit. In the wireless IC device 1C of the third embodiment, the loss of the signal transmitted to the radiator 133 is reduced by arranging the

annular patterns

131a and 131b so as to be coupled to the power feeding circuit and the radiator 133. And a high gain can be obtained. The gain of the wireless IC device 1C with respect to the frequency of the high frequency signal is as shown in FIG. 13, and a high gain is achieved in the UHF frequency band.

Regarding the gain, it is possible to widen the band by changing the position of the coupling point K (see FIG. 9) between the annular pattern 131 and the radiator 133. For example, by setting the position of the coupling point K close to the coupling pattern 132a and increasing the inductance value between the coupling points K, the bandwidth can be increased. This is because if the inductance value between the coupling points K is large, the band between the two resonance points formed by the radiator 133 is widened. In order to increase the inductance value between the coupling points K, the annular pattern 131 may be a meander pattern or a spiral pattern.

Further, since the

annular patterns

131a and 131b are arranged in two layers, more magnetic fields can be generated. Furthermore, since two

annular patterns

131a and 131b and two coupling patterns 132a and 132b are coupled to each other, a plurality of wireless IC devices are close to each other, and a dielectric such as a human hand is close to each other. Even so, the stray capacitance between the patterns is suppressed, and the resonance frequency is prevented from changing. Other functions and effects are the same as those of the first embodiment.

Incidentally, in the third embodiment, the entire antenna 130 resonates at a predetermined frequency. Therefore, when the coupling module 120 is mounted on the coupling patterns 132a and 132b that are part of the antenna 130, the antenna 130 and the coupling module 120 are coupled only by a magnetic field at a predetermined frequency. The antenna 130 and the reader / writer are electromagnetic couplings.

(Other examples)
Of course, the antenna and the wireless IC device according to the present invention are not limited to the above-described embodiments, and various modifications can be made within the scope of the gist thereof.

As described above, the present invention is useful for an antenna and a wireless IC device used in an RFID system, and is particularly excellent in that energy transmission efficiency with the wireless IC is good.

1A, 1B, 1C ...

wireless IC device

10, 110 ...

substrate

20, 120 ... coupling module 21 ...

wireless IC chip

25, 125 ...

feeder circuit substrate

30, 50, 130 ...

antenna

31, 51a, 51b ... coiled

pattern

32a, 32b, 52a, 52b, 132a, 132b ... pattern for

coupling

131a, 131b ... annular pattern 133 ... radiator

Claims

With antenna pattern,
A spiral coupling pattern coupled to the antenna pattern and disposed opposite to each other;
An antenna comprising:
The antenna pattern is a coiled pattern,
The coupling pattern is formed at both ends of the coiled pattern;
The antenna according to claim 1.
The antenna pattern is two coiled patterns arranged to face each other,
The coupling pattern is formed at one end of each of the two coiled patterns;
The antenna according to claim 1.
The antenna pattern is two annular patterns having at least a pair of end portions and arranged to face each other, and has a dipole-type radiator coupled to the annular pattern,
The coupling pattern is formed at one end of each of the two annular patterns;
The antenna according to claim 1.
With antenna pattern,
A spiral coupling pattern coupled to the antenna pattern and disposed opposite to each other;
A coupling module comprising a wireless IC and a power feeding circuit board having a power feeding circuit coupled to the wireless IC;
With
The power supply circuit includes an inductor;
The coupling module is mounted on the coupling pattern;
A wireless IC device characterized by the above.
The antenna pattern is a coiled pattern,
The coupling pattern is formed at both ends of the coiled pattern;
The wireless IC device according to claim 5.
The antenna pattern is two coiled patterns arranged to face each other,
The coupling pattern is formed at one end of each of the two coiled patterns;
The wireless IC device according to claim 5.
The antenna pattern is two annular patterns having at least a pair of end portions and arranged to face each other, and has a dipole-type radiator coupled to the annular pattern,
The coupling pattern is formed at one end of each of the two annular patterns;
The wireless IC device according to claim 5.
The wireless IC device according to any one of claims 5 to 8, wherein the coupling module and the coupling pattern are magnetically coupled.
10. The wireless IC device according to claim 5, wherein the inductor is formed in a spiral shape so that a current flows in the same direction as the coupling pattern.
The wireless IC device according to claim 9 or 10, wherein a resonance frequency of the power feeding circuit substantially corresponds to a resonance frequency of a transmission / reception signal.
The wireless IC device according to any one of claims 5 to 11, wherein a resonance frequency of the antenna pattern is higher than a resonance frequency of the power feeding circuit.
13. The wireless IC device according to claim 5, wherein an area of the coupling pattern is larger than an area of the power supply circuit board.
14. The wireless IC device according to claim 5, wherein the power supply circuit board is made of a material containing a magnetic material.
15. The wireless IC device according to claim 14, wherein the power supply circuit board is formed of a plurality of layers, and the magnetic permeability of the layer on the mounting surface side to the coupling pattern is low.